vīsati

to enter, only in combination with prefixes like upa˚, pa˚, pari˚, saṃ˚, abhisaṃ˚, etc.… See also vesma (house).

viś, cp. viś dwelling-place, veśa; Gr. οίκος house, οἰκέω to dwell; Lat. vīcus, Goth. weihs = E. ˚wick in Warwick, etc.

indeclinable number 20
■ Both forms are used indiscriminately

1. vīsati, e.g. Vin.ii.271 (˚vassa, as minimum age of ordination); Snp.457 (catu-vīsat’akkharaṃ); Ja.i.89 (˚sahassa bhikkhū); Ja.iii.360; Vb-a.191 sq.; Dhp-a.i.4 (ekūna˚, 19); Dhp-a.ii.9, Dhp-a.ii.54; Dhp-a.iii.62 (˚sahassa bhikkhū, as followers); as vīsatiṃ at Dhp-a.ii.61 (vassa-sahassāni).
2. vīsaṃ; e.g. Snp.1019 (˚vassa-sata); Iti.99 (jātiyo) Ja.i.395 (˚yojana-sata); Ja.v.36 (˚ratana-sata); Dhp-a.i.8 Dhp-a.ii.91 (˚yojana-sataṃ).

both for Vedic viṃśati; cp. Av. vīsaiti, Gr. ει ̓́κοσι, Lat. viginti, Oir. fiche, etc.; fr Idg. *ṷi + komt (decad), thus “two decads.” Cp. vi˚